The transition period is critical for the health and productivity of dairy cows due to high incidence of metabolic disorders caused by various bacterial infections. Metabolic disorders are diseases that involve changes in plasma metabolites of sick animals or humans. Almost 50% of dairy cows are affected by one or more metabolic diseases such as ketosis, fatty liver, laminitis, displaced abomasum, milk fever, downer cow syndrome, udder edema, metritis, retained placenta, infertility, or mastitis. The conventional view on metabolic disorders is that these diseases are related to the disturbance of one or more blood metabolites. These changes are generally interpreted as deficiencies or excesses of these nutrients in the diet, especially, around parturition.
High-grain diets (i.e. a diet rich in starch) may be implicated in the development of metabolic disorders. Feeding ruminant animals high-grain diets is a human designed intervention to increase milk and meat production. However, ruminants do not naturally consume high-grain diets; rather, they eat mostly grass or forage diets. Since grain is rich in starch and poor in fiber content, feeding high-grain diets is associated with major changes in the gastrointestinal (GI) microflora switching from fiber-digesting bacteria into starch-digesting bacteria. Most of the starch-digesting bacteria are Gram-negative bacteria. The latter degrade starch to use it for their nutritional needs. During this process large quantities of acids are released into the GI tract, changing the pH from normally alkaline into acidic pH. Furthermore, abundant starch increases the number of Gram-negative bacteria in the GI tract. This is associated with the release of great amounts (20-fold increase) of toxic compounds such as endotoxin or lipopolysaccharide (LPS). Endotoxin translocates into the host's blood circulation and causes a variety of alterations in blood metabolites, immunity, and health status.
Research work indicates that lipoteichoic acid (LTA) is able to induce an inflammatory response and dysfunction of multiple organs, know as septic shock, when administered intravenously (iv) in experimental animals. An early investigation demonstrated that iv infusion of LTA was associated with the release of tumor necrosis factor alpha and interferon gamma in the plasma, a decrease in the arterial oxygen pressure in the lungs, and increases in the plasma concentrations of bilirubin, alanine aminotransferase, creatinine and urea, lipase from pancreas, and creatine kinase. In addition, LTA causes the release of nitric oxide in multiple organs, circulatory failure, and 50% mortality in the experimental animals (De Kimpe S. J. et al., 1995). Moreover, research from different groups has shown that even a single dose of LTA, as little as 0.1 mg, is sufficient to produce enhanced concentrations of free fatty acids (FFA) and triglyceride in the blood of experimental animals. Lipoteichoic acid also has been shown to increase the concentration of cholesterol in the plasma. Additionally, mounting evidence indicates involvement of LTA in the pathogenesis of mastitis in dairy cows. Thus, recent work demonstrated that that infusion of LTA alone in the mammary gland was sufficient to elicit a marked inflammatory response in the mammary gland of dairy cows, characterized by a massive influx of neutrophils into milk. This suggests that during infection, LTA contributes to the recruitment of neutrophils
There remains a need for effective combinations and methods to improve postpartal health and productivity of dairy cows and their newborns.